Scrotal calcinosis: Idiopathic or dystrophic?1. Assistant Professor, Department of Pathology, Army College of Medical Sciences, New Delhi, Delhi, India. email@example.com
Suparna Dubey MD1, Rajeev Sharma MD2, Veena Maheshwari MD3
Dermatology Online Journal 16 (2): 5
2. Consultant Dermatologist, Bishen Skin Centre, Aligarh (UP), India
3. Professor, Department of Pathology, J.N. Medical College, Aligarh (UP), India
Scrotal calcinosis is a rare benign local process characterized by multiple, painless, hard scrotal nodules in the absence of any systemic metabolic disorder. Histological examination reveals extensive deposition of calcium in the dermis, which may be surrounded by histiocytes and an inflammatory giant cell reaction. Numerous theories have been propounded to explain the pathogenesis of this condition, but the principal debate revolves around whether the calcium is deposited at the site of previous epithelial cysts or the calcified nodules are purely idiopathic. This is the largest study of scrotal calcinosis to date with 100 cases, on which clinical, biochemical, radiological, cytopathological, and histopathological examinations were conducted. The histological picture shows a continuous spectrum of changes ranging from intact epithelial cysts (41.0%) – both normal and inflamed; through inflamed cysts containing calcific material in the lumen but with intact cyst wall (53.0%); calcified inflamed cysts with partial epithelial lining (11.0%); to ‘naked’ calcium deposits lying in the dermis (100%), sometimes compressing surrounding collagen fibres to form a pseudocyst (56.0%). The presence of normal values of calcium and phosphorus along with this spectrum of changes in histology both support the theory that these form by dystrophic calcification of epithelial cysts in a progression that involves inflammation, rupture, calcification and obliteration of the cyst wall.
Scrotal calcinosis is a rare benign local process in the absence of any systemic metabolic disorder that is characterized by multiple, painless, hard scrotal nodules. Histological examination reveals extensive deposition of calcium in the dermis, which may be surrounded by histiocytes and an inflammatory giant cell reaction , and in some cases, by a true cyst wall . The exact pathogenesis is yet unknown and theories of origin include idiopathic calcification occurring within normal scrotal collagen , dystrophic calcification of inflamed scrotal epidermoid cysts , eccrine duct milia  or dartoic muscle , and calcification secondary to minor trauma of the scrotum . In various studies, blood analysis, biochemical analysis, and serum electrolyte analysis have been found to be normal and the analysis of intranodular contents showed the common presence of calcium and phosphorus . The condition has been recently reviewed by Shah and Shet , who reported 20 cases and concluded that the etiology is dystrophic calcification. This study of 100 cases attempts to establish dystrophic calcification of epidermal cysts as the mechanism underlying this disorder.
The present study was a combined prospective and retrospective study conducted over a period of 15 years. The prospective study, which spanned 3 years, included 32 cases. All cases clinically diagnosed to be cases of scrotal calcinosis were evaluated and those in which histopathology did not corroborate this diagnosis were discarded, leaving a residual 32 cases. A small, hard nodule was biopsied from each of these 32 patients and a complete clinical, histological and biochemical analysis was undertaken. The retrospective study spanned a period of 12 years and included 68 patients, which were selected by harvesting cases with the histopathological diagnosis of scrotal calcinosis; clinical findings (available in all cases) and the biochemical findings (available in 41 cases) were noted. The harvesting of cases retrospectively was stopped when the number of cases histopathologically diagnosed as scrotal calcinosis reached 100.
The tissue, after being fixed, was partially decalcified in 10 percent HCl (to enable sectioning of block). It was then routinely processed, embedded in paraffin, and sections were stained with hematoxylin and eosin and von Kossa stain. Serum calcium, serum phosphorus, serum albumin, and serum alkaline phosphatase were recorded. A separate Investigational Review Board approval was not obtained from our institution for this study; this is not considered mandatory in our government-run institution like ours.
A. Clinical Evaluation. The age of the patients ranged from 15 to 77 years, with the maximum number of patients – 70 (70.0%) in their third and fourth decade; mean age at presentation was 31.5 years.
Scrotal calcinosis was detected as an incidental finding in 18 percent of patients. Symptomatic patients comprised 82 percent and 72 percent came with concern over the presence of scrotal swellings. Additional complaints of pruritus were found in 22 percent, a history of chalky discharge in 33 percent, and ulceration in 3 percent cases (Table 1).
|Figure 1||Figure 2|
|Figure 1. Multinodular, small, skin colored swellings on scrotum
Figure 2. Multinodular, large, yellowish swellings on scrotum
The duration the presence of the lesions varied from 9 months to 46 years with a mean duration of 8.25 years. Scrotal calcinosis is generally multinodular (45 percent of patients had 11-20 lesions); the maximum number of lesions was 52. The diameter of the largest lesion in each patient was recorded and it varied from less than 1 mm to a large mass 2 x 2.5 cm, with most patients (50.0%) having lesions 6-10 mm in size (Figure 1). The lesions were observed to enlarge and multiply with age (Figure 2). The consistency of the scrotal nodules as perceived on palpation may vary, but 82 percent of patients had stone-hard nodules.
|Intradermal calcified masses with overlying epidermis: (a) basophilic calcified masses (H&E, x50) (b) calcified masses stained black (Von Kossa stain, x50)|
B. Histological Evaluation. A definitive diagnosis of scrotal calcinosis can be made only on the basis of histology, by the presence of von Kossa positive, calcified masses in the dermis (Figure 3). Therefore only the cases with adequate histopathology were included in this study. The histological features of 32 prospectively reported cases are listed in Table 2.
|Figure 4. One large and multiple small deposits of calcium with foreign body reaction in the dermis showing numerous histiocytes (H&E, x125)|
The characteristic feature: amorphous basophilic deposits of calcium ranged from isolated large dermal lesion to multiple small ‘buckshot’ deposits scattered throughout the dermis. The common presentation was that of large deposits with multiple smaller deposits in the periphery (Figure 4).
|Figure 5||Figure 6|
|Figure 5. Foreign body reaction to calcium in the dermis showing numerous histiocytes and foreign body giant cells (H&E, x250)
Figure 6. Histiocytic giant cell, lying at the interphase of calcium and dermis (H&E, x500)
|Figure 7||Figure 8|
|Figure 7. Calcium deposit lined by compressed collagen forming “pseudocyst” (H&E, x125)
Figure 8. Calcium deposit completely lined by flattened stratified squamous epithelium (H&E, x125)
|Figure 9. Calcium deposit completely lined by flattened stratified squamous epithelium (H&E, x125)|
A foreign body reaction to the calcium was also found in all the patients (100%), but it varied considerably in different patients and also in different areas of the same patient, from no or minimal inflammation to florid monocytic / histiocytic infiltrate (Figures 4 and 5) with 59 (59%) patients showing presence of histiocytic giant cell (Figure 6). In 56 (56%) patients, large deposits of calcium were surrounded by compression of the surrounding collagen fibers, giving the appearance of a ‘pseudocyst’ (Figure 7). In none of these cases was keratin found admixed with calcium in these cystic spaces. However, in 60 out of the 100 patients (60%), a true cyst wall composed of compressed stratified squamous epithelium was detected around calcium deposits. It was found to surround the calcifium deposits completely (Figures 8, 9, and 10) in 53 cases (53%) and partially (Figures 11 and 12) in 11 cases (11%); four patients were found to have both types of lining in different deposits.
|Figure 10||Figure 11|
|Figure 10. Calcium deposit completely lined by flattened stratified squamous epithelium (H&E, x125)
Figure 11. Calcium deposit partially lined by flattened stratified squamous epithelium (H&E, x125)
|Figure 12||Figure 13|
|Figure 12. Calcium deposit partially lined by flattened stratified squamous epithelium (H&E, x125)
Figure 13. Large calcified cyst with epithelial cysts of various shapes and sizes (H&E, x50)
|Figure 14. Dilatation and distortion of hair follicle (H&E, x125)|
Additional findings were epithelial cysts of varying shapes and sizes (Figure 13) in 41 patients (41%), both normal and inflamed, and hair follicle abnormalities, dilatation and distortion of follicles (Figure 14). There was a mild inflammatory response in 18 patients (18%) and mild acanthosis and/or hyperkeratosis overlying the calcifium deposits in 31 patients (31%).
C. Biochemical Evaluation. All the biochemical parameters were in the normal range with mean serum calcium of 8.5 mg/dl, mean serum phosphorus of 3.6 mg/dl, mean serum albumin of 4.3 mg/dl and mean serum alkaline phosphatase of 8.2 KAU/100 ml. No other metabolic abnormality was detected.
Clinically scrotal calcinosis may be confused with epidermal inclusion cyst, steatocystoma, cutaneous horn (actinic keratosis), and other benign tumors, such as lipoma, fibroma, angiokeratoma, and lymphangioma circumscriptum; a definitive diagnosis is based on histology. However, the histological pictures in the various studies are often contradictory. A survey of the cases of idiopathic calcinosis of scrotum (ICS) reported in the literature is tabulated (Table 3). The present study of 100 patients with scrotal calcinosis spanning a period of 15 years is one of the largest studies of this entity, which has usually been described in the form of case reports, with just 162 definitive cases reported to date.
Calcinosis of the scrotum was first described in 1883 by H.M. Lewinski  and then in 1888 by Hutchinson , but its nature and cause have remained elusive. Morley and Best  in 1947 subsequently reported a patient with multiple calcified scrotal nodules lined in some areas by a thin layer of stratified squamous epithelium, but unfortunately omitted to include photomicrographs of these areas. Other authors, however, found no evidence of calcified cysts and considered this calcification to be idiopathic . Browne  reported a rare form of dystrophic calcinosis of the scrotum in 4 patients from Africa suffering from onchocerciasis; in two of these dead nematodes were observed in the calcified masses.
However, Shapiro et al.  must be credited with first establishing idiopathic scrotal calcinosis as a distinct entity in 1970 when they gave a comprehensive list of 35 cases, which included 14 new cases and a review of the previous literature. They defined the relevant clinical features. Histological examination showed varying sized masses of basophilic calcified material within the dermis, with empty clefts in some cases and a foreign body granulomatous reaction in others, but none showed evidence of epithelial lining. They stressed the resemblance of the rim of mesenchymal cells around calcifium deposits to flattened epithelium. By chemical analysis, they were able to show the presence of phosphate, carbonate, calcium, and traces of magnesium in the dermal masses, but all patients tested showed normal serum calcium, phosphorus and alkaline phosphatase. The authors felt that the calcinosis was idiopathic in nature, rather than dystrophic or metastatic.
Veress and Malik reported 6 cases of scrotal calcinosis from Sudan with similar clinical and histological features but postulated the hypothesis of a special type of dystrophic calcinosis due to minor pressure or trauma , which was supported by Malcolm  and Feinstein et al. . A foreign body (thorn) was found in one of these cases, which was considered the initiating factor for dystrophic calcification. . Feinstein et al. described a patient with calcinosis and vitiligo of the scrotum, who worked as a farmer and was continuously on a tractor; this was believed to be the source of repetitive trauma. . A history of repetitive trauma or significant trauma preceding the lesions could not be found in any of the patients in our study.
King et al. hypothesized that scrotal calcinosis is due to dystrophic calcification of the dartoic muscle. . Zamora et al. reported an asymptomatic case with massive distortion of the scrotum by calcinosis and postulated that the deposition of calcium on the abnormal mitochondria of injured or dead tissues was important in the etiology. . Malhotra et al. found large numbers of eosinophils in a case they reported and suggested that an inflammatory focus may have preceded the calcification. . Kumagai et al. supported the hypothesis that mast cells and their degranulation could play a role in soft tissue calcification. . However, eosinophils or mast cells were not detected in our study.
Various electron microscopic studies showed deposition of calcium in the ground substance of the extracellular space , within collagen fibrils , on collagen fibrils and within the cytoplasm of fibroblasts [19, 20]. In addition, finely granular mineral deposits but no cellular structures have been reported . Infrared spectrophotometric analysis of the intranodular content by Irisawa et al. showed that it consisted of calcium phosphate (52%) and magnesium ammonium phosphate (48%) . Elemental analysis by x-ray showed the presence of calcium and phosphorus in a ratio varying between 8:1 and 2:1 in the study by Wright et al.  and in the ratio 1.6:1 in the form of densely-packed needle shaped crystals in the study by Ito et al. .
However, the principal debate revolves around whether the calcium is deposited at the site of previous epithelial cysts or the calcified nodules are purely idiopathic.
Cases reported by Fisher and Dvoretzky , Takayama et al.,  Bourland and Clerens (3 cases) , Mehregan (4 cases) , Yahya and Rafindadi (5 cases)  and Hicheri et al.  emphasized the absence of a true cyst wall. More recently, Wright et al. performed immunochemical stains for keratin in 63 lesions from 9 patients of scrotal calcinosis and found no epithelial lining of calcified nodules, concluding that ICS is truly idiopathic .
Several authors have, on the other hand, identified epithelial cysts in the skin of the scrotum showing calcium deposits and have proposed that idiopathic calcinosis of the scrotum is actually caused by ruptured epithelial cysts. After the ambiguous report by Morley and Best , Swinehart and Golitz reported 3 patients in whom scrotal epidermoid cysts coexisted with scrotal calcinosis, suggesting that scrotal calcinosis may represent the end stage of dystrophic calcification associated with the inflammation of scrotal epidermoid cysts. They put forth the contention that there is some quality to the scrotal skin that leads to rapid resolution of epidermoid cysts with calcification . This theory was supported by Bhawan et al., who found evidence of a granulomatous foreign body reaction around keratinous material suggestive of a ruptured epidermal cyst  in a patient originally described as a case of idiopathic calcinosis of the scrotum . Sarma and Weilbaecher , Theuvenet et al. , Saad and Zatari (3 cases)  and Ruiz-Genao et al.  further detected squamous lining around the dermal calcium deposits and this theory of dystrophic calcification of scrotal epidermoid cysts was also supported by the findings of Soldre et al.  and Melo et al. . Song et al., in a report of 51 nodules derived from a single patient, described various forms of cysts-epidermal, pilar, hybrid, and indeterminate types, along with calcification and inflammatory infiltrate, with or without remnants of the cyst wall . Akosa et al. reported 5 cases and suggested that calcification occurs over a period of years in epidermoid cysts that lose their epithelial lining. This suggestion was made on the basis of their findings of intact epidermoid cysts with central calcification, reactions to keratin, and attenuation of the epithelial lining of a cyst, apart from dermal calcified masses . Parlakgumus et al. similarly believed that scrotal calcinosis is due to resorption of cyst wall . In the recent report by Shah and Shet, they assert that most cases of scrotal calcinosis arise from the calcification of preexisting epithelial cysts. The spectrum of changes includes the cystic dilation of the hair follicle, calcification within this cyst, and loss of the epithelial elements with residual areas of calcification, supporting the theory of dystrophic calcification of epidermoid cysts .
Two studies that have supported the theory of dystrophic calcification of epithelial cysts, but only those originating from benign eccrine epithelial cysts, are those of 4 cases by Dare and Axelsen [3, 40] and a single case by Ito et al. .
Dini and Colafranceschi reported a typical case of scrotal calcinosis, which showed a slight positivity of cytokeratin immunostaining (AE1/AE3) in one aggregate of calcified basophilic material. However, they asserted that the term 'idiopathic' should refer to the individual cases that are etiologically undefined rather than the whole category , a view that was supported by Redondo Martinez et al., who reported 3 cases , and Noël et al., who reported 5 cases .
Gormally et al. reviewed the literature up to 1992 and reported 11 new cases, finding a true cyst wall in only one . Michl et al. similarly reviewed the literature up to 1994 and found 12 of 75 patients who had evidence of epithelial lining associated with the calcification . In another review with 5 new cases, published in 1998 by Baruchin et al., none showed epithelial lining. The authors however pointed out that the absence of cysts does not rule out the possibility that they had been there in the earlier stages of ICS . The review published by Yahya and Rafindadi with 5 new cases noted that only 19 out of 100 reported cases had evidence of a true cyst wall or epithelial lining surrounding the calcified nodules . Another analysis was undertaken by Saladi et al., who feel that the pathogenesis of this condition remains equivocal and controversial .
Treatment is limited to surgical excision of the affected part of the scrotal wall, with scrotal reconstruction, if a large area is involved. This is generally curative and relapses are rare.
Based on our observations in 100 cases of scrotal lesions, the diagnosis of scrotal calcinosis is established by the presence of von Kossa positive dermal deposits. But a histopathological spectrum is also observed, which ranges from intact epithelial cysts (41%) – both normal and inflamed, inflamed cysts containing calcific material in the lumen but with an intact cyst wall (53%), calcified inflamed cysts with partial epithelial lining (11%) to ‘naked’ calcium deposits lying in the dermis (100%), with some compressing the surrounding collagen fibers to form a pseudocyst (56%). The fact that true cyst wall and associated epidermoid cysts were more common in the smaller nodules, with the larger calcific masses being 'naked' is also significant. It points toward a plausible explanation for the absence of a cyst wall in 40 percent of our cases and often in the published literature, because excision is generally performed in the late stage, when only the calcified masses remain. The earlier stages may just not have been sampled. Thus, although true cyst walls were found in only 60 percent of our cases of scrotal calcinosis, this spectrum of changes in the histology, coupled with the normal values in the biochemical profile, support the theory of dystrophic calcification of epithelial cysts.These cysts become inflamed, rupture, and calcify, with gradual obliteration of the cyst wall.
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