Localized cutaneous calcinosis associated with leptospirosis in a 4-month-old beagle puppy

Abstract

A 4-month-old male beagle dog was presented for a 15-day history of firm cutaneous nodules. Histopathological examination of skin biopsies revealed calcinosis cutis. However, re-evaluation 40 d later confirmed spontaneous resolution of the lesions without specific treatment. Two weeks before development of the skin lesions, this dog had been hospitalized and treated for acute renal and hepatic disease attributed to leptospirosis, with both PCR and serology positive for Leptospira australis. Calcinosis cutis secondary to a systemic disease (leptospirosis, blastomycosis) has been rarely reported. In this case, the suspected pathogenesis included organic stress (cortisol hypersecretion) and abnormal calcium/phosphorus metabolism during acute renal failure. To our knowledge, this is the third published case of cutis calcinosis associated with leptospirosis in dogs.

Key clinical message:

Previous leptospirosis should be considered in a dog with calcinosis cutis. The cutaneous lesions appeared after acute leptospirosis and regressed spontaneously.

Introduction

Calcinosis, a rare condition in dogs, is defined as deposition of calcium salts in tissues, mainly calcium hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] (1). The term calcinosis is used when this affects the dermis (within the collagen and elastin fibers) or subcutaneous tissues (2). Furthermore, calcinosis is sub-classified as localized or generalized, according to the extent of involvement (3). The pathogenesis of lesion development is poorly understood, but a distinction is proposed between dystrophic cutaneous calcinosis (local inflammation as in chronic proliferative otitis, e.g., hyperadrenocorticism with local alteration of dermal collagen fibers, diabetes mellitus, or a skin tumor), metastatic (disruption of calcium/phosphorus metabolism during renal failure, primary hyperparathyroidism, hypervitaminosis D, or malignant hypercalcemia), iatrogenic (injection of calcium gluconate or progestogens, percutaneous penetration of calcium chloride, or polydioxanone sutures), and idiopathic (usually local tissue damage) (4–6). Rare cases of calcinosis cutis associated with an infectious systemic disease have been reported in the literature: 3 cases of blastomycosis, 1 case of paecilomycosis, and 2 cases of leptospirosis (7–10). We describe the second case associated with leptospirosis in a puppy.

Case description

A 4-month-old male beagle dog was presented for consultation for skin lesions that had appeared 2 mo earlier and did not regress after various antibiotic and antiseptic treatments.

Anamnesis

This puppy had never been treated against internal or external parasites. At 2.5 mo of age, it had received a CHPPiLmulti vaccine (Eurican; Boehringer Ingelheim Animal Health), to confer protection against Leptospira interrogans serovars canicola, icterohaemorrhagiae, and grippotyphosa. One week after vaccination, the puppy had a sudden onset of depression, vomiting, anorexia, and jaundice, requiring emergency hospitalization. The diagnosis was acute renal failure and hepatic disease, based on laboratory evaluations (Table 1) and abdominal ultrasound. Given the lifestyle of this dog, which was frequently walked in a forest with many sources of water, leptospirosis was suspected and subsequently confirmed by a weakly positive RT-PCR examination (< 10² DNA copies) on a urine sample and a significantly positive MAT serology (Micro-Agglutination Test) (antibody titer 1/400) for Leptospira interrogans serovar australis (all other serovars tested, including vaccines, were negative with a titer < 1/100). Medical management included fluids (Ringers Lactate IV), an antibiotic (amoxicillin-clavulanic acid SQ), symptomatic treatments (maropitant IV and aluminum phosphate (Phosphaluvet; Boehringer Ingelheim Animal Health), PO and a refeeding plan (Recovery; Royal Canin) by nasoesophageal tube. Normalization of the general condition and blood parameters associated with renal function (Table 2) prompted removal of the feeding tube and discharge of the dog with the following treatments: doxycycline (10 mg/kg, PO, q24h for 3 wk), and maropitant citrate (2 mg/kg, PO, q24h for 4 d). One week after hospitalization, the dog no longer had digestive clinical signs, but skin lesions appeared that motivated a specialized dermatology consultation 3 wk later (Figure 1).

Table 1.

Modified biochemical end points, at admission, in a 4-month-old male beagle dog with calcinosis cutis associated with leptospirosis. Note that urinalysis, complete blood (cell) count, and abdominal ultrasound were unremarkable.

End point	Result	Normal range
Alanine aminotransferase	168 U/L	10 to 90 U/L
Alkaline phosphatases	600 U/L	10 to 130 U/L
Urea	37.4 mmol/L	3.2 to 10 mmol/L
Creatinine	639 μmol/L	27 to 124 μmol/L
Total bilirubin	38 μmol/L	0 to 14 μmol/L

Table 2.

Renal and hepatic end points in a 4-month-old male Beagle with calcinosis cutis associated with leptospirosis.

End point	D0	D2	D4	D6	D7	D35	Normal range
Urea (mmol/L)	37.4	44.8	22.7	17.1	9.6	4.6	3.2 to 10 mmol/L
Creatinine (μmol/L)	639	427	62	53	48	41	27 to 124 μmol/L
Symmetric dimethyl arginine (g/dL)	—	—	—	—	—	12	0 to 16 g/dL
Alanine aminotransferase (U/L)	168	—	208	—	—	88	10 to 90 U/L
Alkaline phosphatases (U/L)	600	—	603	—	—	90	10 to 130 U/L
Total bilirubin (μmol/L)	38	—	195	108	—	8	0 to 14 μmol/L

Figure 1.

Timeline of events in a beagle dog with calcinosis cutis associated with leptospirosis.

Physical examination

There were no abnormalities detected on the general physical examination, but a dermatological examination revealed 5 nodules, alopecic and indurated, 2 to 8 mm in diameter, on the hind limbs (Figure 2), as well as plaques, well-delimited, firm, and ulcerated, located on the prepuce (Figure 3). The affected skin area was irregularly thickened and partially alopecic. These lesions were neither itchy nor painful.

Figure 2.

Erythematous, alopecic, and ulcerated nodules on the dorsum of the right tarsus of a 4-month-old male beagle dog with calcinosis cutis associated with leptospirosis.

Figure 3.

Coalescent nodules forming ulcerated plaques on the ventral and lateral aspects of the prepuce of a 4-month-old beagle with calcinosis cutis associated with leptospirosis. Note the yellowish material at the periphery of the ulcerated lesions.

Additional examinations

As the lesions strongly suggested cutaneous calcinosis, we conducted the following examinations to confirm this diagnosis: impression smears for cytology, 2 excisional skin biopsies of limb nodules, serum chemistry and endocrine evaluations, and an ultrasound examination of the urinary tract. Differential diagnoses included cutaneous calcinosis as the most likely cause, with nodular demodicosis, dermatophytosis, and cutaneous histiocytosis considered less likely. Skin scrapings, Wood’s lamp test, and trichoscopy were negative, ruling out demodicosis and dermatophytosis. On cytological examination of impression smears of ulcerated lesions, there were inflammatory cells (neutrophils and macrophages), but no evidence of microbial proliferation.

Histopathologic examination of formalin-fixed skin biopsies (stained with hematoxylin-eosin and periodic acid Schiff ) ruled out demodicosis and confirmed cutaneous calcinosis (Figures 4, 5); findings included moderate acanthosis and orthokeratotic hyperkeratosis, with mild to moderate parakeratosis, dermal multifocal deposits of a refringent and cracked basophilic substance, sometimes eliminating through the epidermis and follicular sheaths (2,11,12). This material caused a granulomatous inflammatory foreign body reaction.

Figure 4.

Low-magnification photomicrograph of calcinosis cutis in a 4-month-old male beagle dog with calcinosis cutis associated with leptospirosis. Note the moderate epidermal acanthosis and orthokeratotic hyperkeratosis with mild to moderate parakeratosis, diffuse granulomatous dermatitis with intralesional basophilic granular material typical of mineralized collagen [4-μm tissue section, formalin fixation, hematoxylin and eosin staining (H&E)].

Figure 5.

High-magnification photomicrograph of calcinosis cutis in a 4-month-old male beagle dog with calcinosis cutis associated with leptospirosis. Note the granulomatous reaction comprised of histiocytes organized around basophilic mineral deposits (calcium salts) (4 μm tissue section, formalin fixation, H&E staining).

The serum chemistry profile confirmed normalization of renal [urea, creatinine, Symmetric DiMethyl Arginine (SDMA)] and hepatic (alanine aminotransferase, alkaline phosphatases) functions, as well as an absence of abnormalities in serum concentrations of calcium [112 mg/L; reference range (RR): 78 to 126] and phosphorous (81.9 mg/L; RR: 51 to 104). Spontaneous or iatrogenic hyperadrenocorticism was eliminated by physiological values in the ACTH stimulation test (T0: 134 nmol/L, T0 + 1 h 30 min: 249 nmol/L) and normal adrenal ultrasound. No urinary tract abnormalities were detected with ultrasonography.

Follow-up

In the absence of pruritus and secondary bacterial infection, only a local antiseptic treatment (chlorhexidine and benzalkonium), q12h for 15 d, was used. At re-evaluation 5 wk later, all skin lesions had resolved. No recurrence was observed in the following 3 mo.

Discussion

In dogs, cutaneous calcinosis is most likely due to iatrogenic or spontaneous hyperadrenocorticism (80% of 46 cases in Doerr et al; 12,13). The dog in the current study had not received any local or systemic corticosteroid treatment and ACTH stimulation testing had normal values. Due to the low sensitivity of ACTH stimulation testing, low-dose dexamethasone suppression (LDDS) or urine cortisol to creatinine ratio (UCCR) are considered the best screening tests for spontaneous hyperadrenocorticism. However, ACTH stimulation was used in this case due to the age of this dog, the convenient study duration of 90 min (compared to 8 h for LDDS), and the relative effectiveness in the clinical setting, especially when combined with abdominal ultrasound evaluation.

Cutaneous calcinosis in dogs is only rarely attributed to systemic infections due to fungi (blastomycosis, paecilomycosis) or bacteria (leptospirosis) (7–9). So, here we describe the third case of cutaneous calcinosis associated with leptospirosis, the second in a puppy. For this case, the mechanism of calcium deposition remains hypothetical:

• dystrophic calcinosis due to cortisol hypersecretion in connection with the organic stress induced by the systemic disease;

• potential metastatic calcinosis linked with a calcium/phosphorous imbalance (hyperphosphatemia) during the acute crisis of renal failure (unfortunately, serum calcium and phosphorous concentrations were not measured during the acute episode); or,

• idiopathic calcinosis, rarely described in dogs < 1 y and which could have been due to transient physiological hyperphosphatemia (14,15).

In our opinion, a combination of several of these factors likely caused the observed lesions.

Irrespective of the underlying cause, clinical aspects of cutaneous calcinosis are quite characteristic, and include papules, nodules, or plaques that are firm, erythematous, and secondarily ulcerated. These lesions are either solitary or multicentric, and vary from 5 mm to 8 cm. A whitish or yellowish color, visible also after incision of a lesion or extrusion by pressure, is suggestive of mineral deposition. In the first published case of calcinosis cutis associated with leptospirosis, a 6.5-year-old German shepherd was presented 2 mo after an episode of leptospirosis (hepatitis and acute renal failure) with 1- to 2-mm white papules within irregularly thickened alopecic areas, extending over 40% of the surface of the back and perineal region (generalized form). These lesions spontaneously regressed within 2 mo and no recurrence was observed within 9 mo. The cutaneous signs observed in our puppy also corresponded to a generalized form (3 sites), although less extensive, of rather unusual sites (limbs, prepuce), since classical affected areas include the dorsal cervical region, back line, ventral abdomen, and axilla. Following blastomycosis, lesions of calcinosis cutis were either generalized (2 cases) or localized (1 case).

Despite the inherent limitations of extrapolating from only 2 cases, cutaneous calcinosis associated with leptospirosis seemed to appear later (2 to 8 wk after the onset of disease) and to experience a favorable course with spontaneous regression of skin lesions within 7 to 9 wk after their initial appearance, suggesting that some localized forms may be unnoticed and therefore the condition underdiagnosed. There does not appear to be any specificity of the variant in the onset of cutaneous calcinosis, since the cases reported by Munday et al (9) and Michel et al (10) were not vaccinated and were infected with Leptospira copenhageni and Leptosira icterohaemorrhagiae, respectively, whereas the puppy in this article was infected with Leptospira australis, an antigen that was not included in the vaccine administered. It should be noted that 2 other cases of cutaneous calcinosis associated with canine leptospirosis were reported (but never formally published) at an annual meeting of the American Association of Veterinary Pathology in 2009; these were due to Leptospira icterohemorrhagiae in 1 dog and serovar not determined in the other) (16). Surprisingly, these 2 cases were also beagles, which may suggest a breed predisposition, although the limited number of reported cases precluded a firm conclusion.